Abstract

The observed mass-independent sulfur isotopic composition (Δ33S) of volcanic sulfate from the Agung (March 1963) and Pinatubo (June 1991) eruptions recorded in the Antarctic snow provides a mechanism for documenting stratospheric events. The sign of Δ33S changes over time from an initial positive component to a negative value. Δ33S is created during photochemical oxidation of sulfur dioxide to sulfuric acid on a monthly time scale, which indicates a fast process. The reproducibility of the results reveals that Δ33S is a reliable tracer to chemically identify atmospheric processes involved during stratospheric volcanism.